China will receive its first batch of S-400 Triumph long-range anti-aircraft missile systems within the next 12 to 18 months, TASSreports.

“Supplies are planned no earlier than in a year, or more likely, in a year-and-a-half,” a Russian defense industry source told TASS last Thursday.

The signing of the contract for four to six S-400 Triumph (NATO reporting name: SA-21 Growler) missile defense systems was officially announced this April, although the deal was likely already concluded in the first quarter of 2014. The contract value is estimated at about $3 billion.

Additional details on the Sino-Russia arms deal, however, are difficult to come by. Back in April, Director General of arms exporter Rosoboronexport Anatoly Isaykin merely told reporters that he “would not disclose the contract details, but yes, China has indeed become the first buyer of the Russian newest air defense system, which only emphasizes the strategic level of our relations.”

One of the major outstanding questions remains what type of missile Russia will sell to China for the S-400 Triumph missile defense systems. As J. Michael Cole pointed out in a piece for The Diplomat, the much discussed 40N6 missile is said to have an operational range of 400 km (248.5 miles) but it is not clear whether the weapon is even operational in Russia yet. “An alternative to the 40N6 would be the 48N6 series, whose range is much more limited, at 250 km,” Cole notes. The system can purportedly fire three types of missiles and simultaneously engage 36 targets.

In April, Defense Newsemphasized that the new weapon, if outfitted with 40N6 missiles, will greatly increase China’s air defense space, particularly in the East China Sea:

The 400-kilometer-range system will, for the first time, allow China to strike any aerial target on the island of Taiwan, in addition to reaching air targets as far as New Delhi, Calcutta, Hanoi, and Seoul. The Yellow Sea and China’s new air defense identification zone (ADIZ) in the East China Sea will also be protected. The system will permit China, if need be, to strike any air target within North Korea.

However, in his analysis Cole points out that this might be an overstatement: even if “Moscow would agree to sell the 40N6 missile, it would be very difficult for the new SAM system to cover all the cities and areas listed in the reports.” He continues:

The Senkakus, for example, are located 200 nautical miles (370 km) east of the Chinese mainland, thus at the very edge of the maximum operational range of the 40N6. The distance between New Delhi, another city named in the reports, and the Chinese border is about 400 km; moreover, to bring the Indian capital within range, not only would China need to deploy the S-400 right at the border — a not uncontroversial move — it would have to perform the difficult feat of deploying the system…in the middle of the Himalayas!

According to TASS, India has also expressed an interested in purchasing 12 S-400 Triumph defense systems.